Interconnected circuit breakers



July 23, 1963 N. J. SCHWARTZ 3,098,910

INTERCONNECTED CIRCUIT BREAKERS Filed July 1, 1960 3 Sheets-Sheet l INVENTOR. NORMA/V J. SCHWAIP Z 1.5 A Tram/EX July 23, 1963 J, SCHWARTZ 3,098,910

INTERCONNECTED CIRCUIT BREAKERS 3 Sheets-Sheet Filed July 1, 1960 INVENTOR. NORMAN J, SCHWARTZ BY HAS A TTO/P/VEX United States Patent Jersey Filed July 1, 1960, Ser. No. 40,380 7 Claims. (Ql. 2l)0106) This invention relates to circuit breakers and in particular to multipole circuit breakers of the type in which each pole of the circuit breaker is constructed of units that are similar. One object of the present invention is to provide an improved, simple, and inexpensive arrangement for interconnecting the poles of such circuit breakers.

Another object of the present invention is to provide an interconnecting device in which the force to initiate action in the tripping direction is no greater than that needed to actuate any one of the poles.

In one embodiment, the invention is incorporated in three similar circuit breakers each having a toggle linkage for operating the movable contact. Further, each has an electromagnetic coil which, upon a predetermined overload, attracts an armature that trips the toggle linkage and allows the movable contact to move relative to the stationary contact, under the bias of a spring.

The linkage of the circuit breaker impinges, during the tripping, upon a pivotal member. Each of the breakers of the multipole unit is provided with similar pivotal members, all of which are interconnected, and each pivotal member is associated with one armature. When the first pivotal member is actuated, by impingement therewith of the linkage, it causes all of the others to rotate into contact with their associated armatures, moving each armature in the tripping direction for opening the contacts of all of the poles substantially simultaneously.

Thus, it is seen that the tripping action of the overloaded pole is applied only against the spring force tending to maintain that particular pole in the contacts closed position. All of the contacts of all the poles are opened due to the fact that all the armatures are rotated in the latch releasing direction by the rotation of the common trip bar.

The foregoing and other objects of the invention, the principles of the invention, and the best modes in which I have contemplated applying such principles will more fully appear from the following description and accompanying drawings in illustration thereof.

FIG. 1 is a perspective view illustrating a multiple circuit breaker unit construe-ted in accordance with the present invention, omitting the master handle and part of the associated interconnecting rod and also cutting away some of the other parts;

FIG. 2 is a partial side elevation, partly in vertical section, taken adjacent an end pole and adjacent the central master handle of the circuit breaker unit illustrated in FIG. 1 and showing the contacts in the closed position;

FIG. 3 is a view similar to FIG. 2 but showing the position of the mechanism after tripping thereof but before automatic resetting;

FIG. 4 is a view similar to FIG. 3 but showing the open position of the contacts;

FIG. 5 is a partial perspective view showing one of the circuit breakers in the contacts closed position;

FIG. 6 is a partial sectional vie-w taken along the line 6k6 in FIG. 2, looking in the direction indicated by the arrows; and

FIG. 7 is a side elevation of a portion of the support structure -for the circuit breaker mechanism.

Referring to the drawings, this invention is embodied in a multipole circuit breaker unit comprising a metallic casing 20 enclosing the similar circuit breakers 21, 22 and 23. The components of each of the aforementioned cir 3,398,910 Patented July 23, 1963 cuit breakers are substantially the same and only those components of one circuit breaker, circuit breaker 21, will be described in detail, it being understood that the others are similar. However, when necessary to clarify the description, the components of the other circuit breakers will be mentioned with the prefix 1 added for circuit breaker 22, and the prefix 2 added for circuit breakers 23, to better distinguish the various parts.

The circuit breaker 21 is provided with terminals 25 and 26 for connecting the unit to a desired circuit. The terminal '25 is connected to a stationary contact 27 which cooperates with a movable contact 28, the latter being carried by a movable arm 29. The movable arm pivots about a fixed pintle 31 and is biased by a spring 32 to the open position of the contacts.

The movable arm 29 comprises part of a linkage mechanism which includes a toggle 33 comprising links 35 and 36. The link 35 is pivotally connected to the movable arm 29 at one end and to the link 36 at the other end to form the knee 37 of the toggle. The link 36 is pivotally connected at the other end to the handle link 38 by a pintle 39. The link 38 oscillates about a fixed pivot 41 supported by extending through openings in the vertical opposed supporting walls 42, the latter being mounted on insulating bases 43 supported by the bottom of the case 20. The handle links 38, 138 and 238 of the three circuit breakers are interconnected by an insulator rod 44 pivotal and slidable in elongated slots 45. The insulator rod 44 is securely connected at its middle portion to a master pivotal handle 47 (FIG. 2) projecting through a neck 49 added to the casing 20. The handle links are biased to the off position of the contacts by a torsion spring 5-1 wound about the pivot 41 and having one end held stationary in a notch in one of the walls 42 and the other end under the pintle 39 at the connection between the link 38 and the link 36. The master handle '47 may be pivoted about a fixed pintle 52 carried by the neck 49. By soldering all the joints of the casing 20 and providing a rubber diaphragm 53 to the left of the fixed pintle 52 a sealed unit results, FIGS. 3 and 4.

The toggle link 36 is provided with a tooth portion 54 for engaging a half moon 55 of a latch 56 carried by the link 35 for locking the toggle in the overcenter position during automatic resetting. The latch 56 is biased in the clockwise direction, as viewed in FIG. 2, by a spring 57 (FIG. 6).

The latch 56 is tripped by an armature 59 having a right-hand portion 60, as viewed in FIG. 2, which engages the latch 56 upon an overload and turns it against the bias of the spring 57 to present the fiat portion of the half moon 55 to the tooth 54 thereby allowing the toggle 33 to collapse upwardly under the bias of the spring 32.

p The armature left-hand end 69 (FIG. 2) is attracted, upon o verload, toward the pole piece -61 of an electromagnet comprising a coil 62 formed about a tube 63, the latter projecting through a leg 64 of an L-shaped frame 65. The tube 63 houses a movable magnetic core biased to the right-hand end of the tube to provide a time delay below certain overload currents before tripping of the unit. The L-shaped frame 65 is provided with lugs 66 extending through the vertical support walls 42 and the coil 62 has one end connected to the movable contact by a flexible conductor 67 and the other end connected by a conductor 68 to the terminal 26.

The tripping of the adjacent poles is eifected upon the automatic tripping of any one pole through the pivotaltrip levers 70, and 270 and the interconnecting common insulator bar 71. Referring to one of the trip levers, the trip lever 70 is formed fromwire (circular in cross section) of suitable rigidity and is turned upon itself to provide a bearing 72 at approximately its midpoint for pivoting the lever 70 about the fixed pintle 41. The

upper end portion 73 has a slanted portion and another portion 74 turned at a right angle to the body of the lever 70, as illustrated in FIGS. 2 and 6.

The right angle portion 74 is disposed above the knee 37 of the toggle 33 but spaced therefrom in the closed position of the contacts 27 and 28. The other end portion 76 of the trip lever 70 is also turned at a right angle to the body of the trip lever 70 and has a foot 77 engagea-ble with the end portion 69 of the armature 59 which moves toward the pole piece 61 upon overload.

The armature 59 is biased by a spring 79 so that the end 60 of the armature is urged away from the latch 56 and the end 69 is biased clockwise toward the foot 77 and against a rectangular limiting stop 78 turned out from one of the walls 42. The spring 79 has one end abutting a shaft '81 connecting the spaced generally L-shaped armature members 82 and the other end of the spring 79 is disposed in a slot 83 formed in one end portion of the armature pivot 84 carried by the walls 42. The other end portion of the pivot 84 is connected to a spring 86 for holding the pivot stationary, the ends of the spring 86 being held stationary in a notch in one of the walls 42.

The weight of the various parts of the trip lever 70 and the bar 71 are such that a force is exerted when the apparatus is disposed with the terminals 25 and 26 at the bottom (as illustrated in FIG. 1), about the pintle 41 tending to bias the lever 70 in the clockwise direction against a rectangular limiting stop 87 formed in one of the walls 42 generally opposite the stop 78 for the armature 59, FIG. 6. The end portion 76 of the lever 70 is proportioned and positioned relative to the stops 7-8 and 87 and the armature end 69, so that a slight clearance exists between the foot 77 and the armature end 69 when the circuit breaker is in the closed position of the corrtacts, as illustrated in FIG. 2, to prevent accidental tripping of the circuit breakers due to vibration or shook. As illustrated in FIG. 4, the clearance between foot 77 and armature end 69 also exists in the open position of the contacts.

If desired, torsion springs (not illustrated) may be wound about one or all of the three pintles 41, 141 or 241 having spring ends in contact with the bar 71 and other ends secured in notches in the vertical walls, 42, 142 and 242 for increasing the bias of the foot 77 toward the stop 87.

Upon an overload in any one pole, for instance, the pole illustrated in FIG. 2, sufiicient to trip the pole, the armature 59 is rotated about its pivot 84 into engagement with and rotates the latch 56 against the bias of the latch spring 57 sufficiently for the tooth 54 to clear the half moon 55. The ovencenter toggle 33 immediately collapses under pressure from the opening spring 32. The collapse of the toggle 33 and its movement through the space between the lever end 74 and the channel shaped portion 89v of the link 35, causes the portion 89 to forcefully impinge upon the lever end 74, for rotating the lever 70 and, through the bar 71, the associated levers 170 and 270 of the adjacent poles.

Rotation of the adjacent levers 170' and 270 causes their associated armatures to move in the direction to release their toggles by rotating the associated latches in the toggle releasing direction. Thus, it is seen that the initial force required to trip the first or overloaded pole is no greater than the force which would be required to trip the circuit breaker if it were not associated with other circuit breakers, i.e., the force required to rotate one latch against its own spring. Also, the force to .rotate all of the trip levers and the connecting bar 71 is derived from the opening spring 32. Since the opening spring 32 is made strong enough to open the contacts under possible adverse circumstances, a reservoir of power is available sufficient to rotate all the trip levers and interconnecting bar.

FIG. 3 illustrates the overload p oleirnmediately after 4 tripping and after the toggle 33 has impinged upon the end 74 and rotated the three levers 70, 170 and 270 of the multipole circuit breaker in the contacts opening direction.

FIG. 4 illustrates the overloaded pole after the mechanism has been reset due to the bias of the spring 51. The spring 51 forces the link 38 to rotate, moving the handle 47 to the off position and the toggle 33 to the reset position wherein the tooth 54 is restrainably engaged by the half moon 55.

It is to be noted that the opening of all three poles occurs substantially simultaneously since the time lead of the overload pole, for instance circuit breaker 21, is the amount of time required for the toggle 33 to travel the clearance distance between the channel shaped portion 89 and impinge upon the lever end 74 plus the time required to travel through the slight clearance between foot 77 and armature end 69 and thereafter to rotate the armatures and latches of the associated, nonoverloaded circuit breakers 22 and .23. Upon the rotation of the latches of the circuit breakers 22 and 23 the toggles thereof also'. collapse and their contacts start to open. Thus, by properly proportioning the various parts, the contacts of the nonoverloaded circuit breakers start to open before the contacts of the overloaded circuit breakers are entirely open, resulting in a substantially simultaneous opening of the contacts of all the poles of the unit.

While FIGS. 3 and 4 have been discussed in connection with the overloaded pole it is seen that the positions of the mechanism (immediately after tripping and in the off position of the contacts) are the same whether the tripping occurs due to the overload being in the pole illustrated or in an adjacent pole.

The trip lever 7 0 is formed from a suitable material to provide for deformation of the lever ends 73 and 76 upon final assembly and testing so that manufacturing variations may be compensated for and calibration of the circuit breakers made.

Movement of the mechanism in the opening direction is limited by abutment of the movable contact arm 29 with the horizontal portion of the frame 65. Similarly in the closed position of the contacts, the mechanism is held in a stable position by abutment of the ends of the pivot 39 connecting the link 38 to the link 36 with a portion of the vertical walls 4 2, as illustrated in FIG. 7. Also illustrated in FIG. 7, in dotted lines, is the position of the pivot 39 when the mechanism is in the contacts open position showing that the ends of the pivot 39 are spaced from the walls 42 in this position, the walls 42 being provided with suitable openings 90.

Referring to FIG. 2, the insulator bar 71 is securely connected to the trip lever 70, below the bearing 72 and between the bearing 72 and the end portion 76 by turning the wire upon itself to form a bearing-like portion which firmly grips the insulator bar 71.

From the foregoing it is seen that the pivot 41 of the operating mechanism is utilized to provide a pivotal connection for the trip lever 70. The trip lever 70 may be thought of as comprising two portions one above and one below the pivot 41. The portion above the pivot 41 is actuated by the mechanism of the circuit breaker when the circuit breaker is tripped upon an overload occurring in its coil. The portion below the pivot 41 is connected to a bar 71 for tripping the circuit breakers (adjacent to the one which is overloaded) by moving all of the armatures in the direction to release all of the latches from restraining engagement with all of the link teeth.

Also, the portion of the trip lever above the pivot 41 is generally disposed above the handle link 38 and the toggle 33, FIG. 2 (with no part of the operating mechanism directly above the end portion 73), so that if minor adjustments have to be made to the end portion 73 they can be readily made. Likewise, since the end portion 76 is to one side of the armature end 69 with no part of the operating mechanism between it and the casing 20, ad-

justments may be readily made to the end portion 76, if needed.

If desired, the interconnecting bar 71 may be connected to the trip levers 71), 170 and 270 between the pivot 41 and the trip lever end 73 but is not so illustrated. For this purpose, this portion of lever 70' is bent and the connection to bar 71 made so that during all positions no interference will result and a suitable slot (not illustrated) is made in the walls 42, 142 and 242 to accommodate the bar 71.

It will be noted that the mechanism remains trip free in that if the master handle 47 is turned toward the closed position of the contacts while an overload current persists in one of the poles, all of the contacts will move to the open position of the contacts. The foregoing occurs because the iarmature of the overloaded pole will rotate its latch and its toggle will collapse, followed by impingement of the collapsed toggle upon the trip lever, resulting in the collapse of the associated toggles of the associated circuit breakers, as heretofore stated. Thus, all of the contacts move to the open position even if, for example, the master handle is manually maintained thereafter in the position corresponding to the closed position of the contacts.

The circuit breakers 21, 22 and 23 are electrically spaced from each other and the metallic casing 20 by being supported by the insulator bases 43 on the base of the casing 20 and physically spaced from the other walls of the casing 20 and each other. 'If desired, insulator spacers (not illustrated) may be placed in these spaces and/ or the casing may be formed of an insulating material.

Summarizing, it is seen that the master handle 47 iscapable of moving the operating mechanism of all three circuit breakers to open or close the contacts of all three circuit breakers, independently of the trip levers 70, 170 and 27d and interconnecting bar 71. If the contacts of all the circuit breakers have been moved to the closed position, and an overload occurs in one of the coils, the armature of the mechanism associated with this coil will be rotated, referring to FIG. 2, so that the armature end 69 moves toward the pole piece "61 and the armature end 60 rotates the latch 56. Rotation of the latch 56 allows the toggle 33 to collapse and the movable contact 28 to start its opening movement. Substantially simultaneously with the initial opening movement of the contact 28, the channel portion 89 of the link 35 traverses the space between the link 35 and the right angle portion 74 and forcefully impinges on the portion 74. This impingement causes all of the trip levers 70, 170 and 270 to rotate in the direction tending to rotate all the armatures in the direction necessary to remove the restraint of the latches (of the untripped poles) from their associated toggles, whereupon the associated toggles (of the poles other than the overloaded pole) collapse and their associated contacts open also, substantially simultaneously with the opening of the contacts of the overloaded pole. After the opening of all of the contacts, the spring 51 moves the master handle 47 to the oil? position and simultaneously automatically resets the toggle.

Having described this invention, I claim:

1. The combination of a plurality of similar switch units, each switch unit having a pair of relatively movable contacts, an automatically resettable mechanism including a toggle linkage operatively connected between one of said contacts and a manual operator, an overload sensing and toggle tripping device associated with said toggle linkage, said toggle linkage being collapsible by said device to a position for opening said contacts, an automatically resettable movable common trip member associated with each overload sensing device, each toggle linkage being independent of the associated movable common trip member in that the former is out of force transmitting relationship with the latter in the closed and open positions of the contacts and in force transmitting relationship therewith only during the collapsing movement of the toggle linkage, each of said movable common trip members being interconnected, whereby the collapsing movement of the associated toggle linkage for opening said contacts of one switch unit also moves all of the other common trip members of the associated switch units in the direction necessary to cause all of their associated toggle linkages to collapse and move to the contacts open position.

2. The combination of a plurality of similar switch units, each switch unit having a pair of relatively movable contacts, an automatically resettable toggle linkage operatively connected between one of said contacts and a manual operator, an overload sensing and toggle tripping device associated with said toggle linkage, said toggle linkage being collapsible by said device to a position for opening said contacts, an automatically resettable movable common trip member associated with each overload sensing device, each toggle linkage being independent of the associated movable member in that the former is spaced from the latter in the closed and open positions of the contacts and engageable therewith only during the collapsing movement of the toggle linkage, each of said movable members being interconnected, whereby the collapsing movement of the associated toggle linkage for opening said contacts of one switch unit also moves all of the other common trip members of the associated switch units in the direction necessary to cause all of their associated toggle linkages to collapse and move to the contacts open position.

3. The combination of a plurality of similar switch units, each switch unit having a pair of relatively movable contacts, an automatically resettable linkage mechanism including a toggle linkage operatively connected to one of said contacts and a reset spring, said toggle linkage including a latch, a spring biasing said latch to the latched position, an overload sensing and toggle tripping device associated with said toggle linkage, said toggle linkage being collapsible by said device to move said linkage mechanism to a position for opening said contacts, a movable common trip member operatively associated with each overload sensing device and each linkage mechanism in that during movement of the unlatched linkage mechanism to the contacts open position the latter moves the common trip member of the initially overloaded switch unit which in turn moves the overload sensing device of the associated switch unit, each toggle linkage being independent of the associated movable common trip member in that the former is spaced from the latter in the closed and open positions of the contacts and relatches under the bias of said reset spring after the collapsing movement of the toggle linkage and upon the termination of the overload, each of said movable members being interconnected, a third spring for resetting said common trip member after said toggle linkage resets, whereby the collapsing movement of the associated toggle linkage for opening said contacts of one switch unit also moves the common trip member of the associated switch unit in the direction necessary to cause the associated toggle linkage to collapse and move to the contacts open position.

4. The combination of a plurality of similar switch units, each switch unit comprising an armature, an electromagnet having a coil for attracting said armature upon a predetermined overload, relatively movable contacts, an automatically resettable linkage mechanism movable to open and close said contacts, said linkage mechanism including a latch for maintaining said linkage mechanism in the contacts closed position, said armature being attractable upon overload for tripping said latch, an automatically resettable common trip member having a portion in the path of movement of said linkage mechanism and impingeable thereby upon the tripping of said latch, said common trip movable member being rotatable by said linkage mechanism upon the tripping of the latch, the common trip movable members of the switch units being interconnected so that movement of one causes the movement of the others, each common trip movable member having a second portion adjacent the associated armature for rotating the armature in the direction to unlatch the associated mechanisms for opening the contacts of the switch units other than those of the switch unit which initiates the rotation of the movable member, the portion of said movable member impinged upon by said linkage mechanism being at all times disposed outwardly of the path of movement traversed by the portion of the linkage mechanism which impinges on the movable member, the portion of the linkage which impinges upon the movable member and the portion of the armature acted upon by the movable member being disposed at all times intermediate the two portions of the movable common trip member mentioned, and the movable member being pivotal on a pintle intermediate the two portions mentioned.

5. The combination of a plurality of similar switch units, each comprising an armature, an electromagnet having a coil for attracting said armature upon a predetermined overload, relatively movable contacts, an automatically resettable linkage mechanism movable to open and close said contacts, said linkage mechanism including a latch for securing said linkage mechanism, said armature being attractable upon overload for tripping said latch, an automatically resettable pivoted elongated common trip wire having one end portion in the path of movement of said linkage mechanism upon tripping thereof, said elongated wire being rotated by said linkage mechanism upon the tripping of the latch, the elongated wires of each switch unit being interconnected so that movement of one causes the movement of the others, eachv elongated wire having another end portion biased toward the associated armature for rotating the armature in the direction to unlatch the associated mechanism for opening the contacts of the switch units other than those of the switch unit which initiates the rotation of the movable member, the end portions of each elongated wire bounding the paths of movement traversed by the portions of the associated linkage mechanism and the associated armature.

6. A multi-pole circuit breaker comprising in combination a plurality of similar units each comprising a pair of contacts, a means for sensing electrical overload, a toggle mechanism for moving one of said contacts, said toggle mechanism including a latch for securing said toggle mechanism, an armature operatively associated with the sensing means for tripping said latch, a spring for biasing the movable contact to the contacts open position, a pivotal common trip member having a portion disposed in the path of movement, and impinged by, said toggle only when the latch is tripped, said toggle being capable of rotating said pivotal member at such time, said pivotal member having a second portion capable of engagement with said armature for rotating said armature in the tripping direction, said pivotal member portions bounding the path of movement of the toggle mechanism and the armature, respectively, whereby adjustments to the pivotal member portions may be readily made during assembly, and a shaft interconnecting the pivotal members, whereupon an overload in any one electromagnet and the pivoting of its associated armature and the tripping of the associated latch, the associated toggle impinges on the associated pivotal member and rotates the interconnecting shaft for moving the pivotal members of the other units in the direction to impinge upon and move their armatures in the direction to trip their associated latches for substantially simultaneously opening the contacts of all of the units.

7. The combination of a plurality of similar switch units, each switch unit having a pair of relatively movable contacts, an automatically resettable linkage mechanism including two relatively movable members, a latch therefor, a latch spring biasing said latch to the latched position, and a reset spring for said linkage mechanism,

said linkage mechanism being connected to one of saidcontacts for opening and closing the contacts, an overload sensing and latch tripping device associated with said linkage mechanism, said linkage mechanism being movable upon unlatching thereof to a position for opening said contacts, a movable common trip member operatively associated with each overload sensing device and each linkage mechanism in that during unlatched movement of the linkage mechanism to the contacts open position the latter moves the common trip member of the initially overloaded switch unit which in turn moves the overload sensing and latch tripping device of the associated switch unit, said relatively movable members being independent of the associated movable common trip member in that theformer are spaced from the latter in the closed and open positions of the contacts and relatch under the bias of said reset spring after the movable members have been unlatched and the termination of the overload, each of said movable members being interconnected, whereby the collapsing movement of the associated toggle linkage for opening said contacts of one switch unit also moves the other common trip member of the associated switch unit in the direction necessary to cause the associated linkage mechanism to unlatch and move to the contacts open position.

References Cited in the file of this patent UNITED STATES PATENTS 2,797,277 Dorfman et a1 June 25, 1957 2,811,607 Dorfman et al. Oct. 29, 1957 2,824,191 Christensen Feb. 18, 1958 2,889,428 Kingdon et al. June 2, 1959 2,932,706 Bodenschatz Apr. 12, 1960 

1. THE COMBINATION OF A PLURALITY OF SIMILIAR SWITCH UNITS, EACH SWITCH UNIT HAVING A PAIR OF RELATIVELY MOV/ ABLE CONTACTS, AN AUTOMATICALLY RESETTABLE MECHANISM INCLUDING A TOGGLE LINKAGE OPERATIVELY CONNECTED BETWEEN ONE OF SAID CONTACTS AND A MANUAL OPERATOR AN OVERLOAD SENSING AND TOGGLE TRIPPING DEVICE ASSOCIATED WITH SAID TOGGLE LINKAGE, SAID TOGGLE LINKAGE BEING COLLAPSIBLE BY SAID DEVICE TO A POSITION FOR OPENING SAID CONTACTS, AN AUTOMATICALLY RESETTABLE MOVABLE COMMON TRIP MEMBER ASSOCIATED WITH EACH OVERLOAD SENSING DEVICE, EACH TOGGLE LINKAGE BEING INDEPENDENT OF THE ASSOCIATED MOVABLE COMMON TRIP MEMBER IN THAT THE FORMER IS OUT OF FORCE TRANSMITTING RELATIONSHIP WITH THE LATTER IN THE CLOSED AND OPEN POSITIONS OF THE CONTACTS AND IN FORCE TRANSMITTING RELATIONSHIP THEREWITH ONLY DURING THE COLLAPSING MOVEMENT OF THE TOGGLE LINGAGE, EACH OF SAID MOVABLE COMMON TRIP MEMBERS BEING INTERCONNECTED, WHEREBY THE COLLAPSING MOVEMENT OF THE ASSOCIATED TOGGLE LINKAGE FOR OPENING SAID CONTACTS OF ONE SWITCH UNIT ALSO MOVES ALL OF THE OTHER COMMON TRIP MEMBERS OF THE ASSOCIATED SWITCH UNITS IN THE DIRECTION NECESSARY TO CAUSE ALL OF THEIR ASSOCIATED TOGGLE LINKAGES TO COLLAPSE AND MOVE TO THE CONTACTS OPEN POSITION. 